Recent genetic studies show that at least one of the mutations that produced light skin and hair was already prevalent among Neanderthals prior to the arrival of early modern humans in Europe.
Similar studies also show that two of the three mutations were widespread in early modern humans in northern Europe by about 10,000 years ago, but not in southern Europe until about 5800 years ago.
Given that these are relatively recent discoveries, I would expect to see depictions of southern (warm-climate) Europeans start to show darker skin than they have so far, while those of northern (cold-climate) Europeans remain as they are.
It really has been a very strongly selected characteristic, tied to the local climate.
The primary reason you haven't seen them depicted this way so far, is that prior to these recent discoveries it was presumed to have happened much earlier than it did. Prior to the split between Europeans and East Asians.